<p>
    You can create 16px and 32px icons by opening a vector icon in Icon-O-Matic and
    export as PNG 16x16px and PNG 32x32px. Opening the vector icon is most easily
    done by opening the app's binary sporting the icon with the FileType Tracker
    addon and double-clicking the icon there.
</p>

<p>
    The HVIF icon file is created in the same way, by exporting as HVIF from
    Icon-O-Matic.
</p>

<p>
    You can extract 16px and 32px icons from an app that doesn't have a vector icon
    (i.e. from an old BeOS icon) by using the commandline tool app2png, available
    from the HaikuDepot.
</p>